One such device by American Medical Systems, Inc. is the AUS 800, which is a totally implantable hydraulic sphincter implanted in both males and females experiencing urinary incontinence and has been on the market for over 35 years. The AUS 800 and its predecessors are described in U.S. Pat. Nos. 3,863,622; 4,222,377; 4,412,530; and 4,878,889. The AUS 800 consists of a silicone pressure regulating balloon implanted in the prevesical space, a silicone control pump implanted in the scrotum or labia, and a silicone urethral occlusive cuff wrapped around the bulbous urethra in males or bladder neck in females. Each component is filled with saline or radiopaque contrast media. Tubing, emanating from each component, is routed between incisions and appropriate connections are made. The device is deactivated for a period of approximately 6 weeks to allow tissue healing to proceed and urethral edema to subside. At activation, the control pump is squeezed sharply to unseat a poppet and open operational fluid flow paths. The patient is taught to operate the device by squeezing the control pump through the scrotal or labial skin. This action transfers fluid from the cuff to the pressure regulating balloon. The balloon forces the fluid through a fluid restrictor and back into cuff to reestablish an occlusive urethral pressure within 3-5 minutes. The AUS 800 is complicated to implant, is prone to fluid leakage, and causes urethral atrophy and erosion. Despite these draw backs, the AMS 800 is the only commercially available artificial urinary sphincter.
Another such type of mechanical artificial urinary sphincter, the Timm-AUS, is described in U.S. Pat. Nos. 5,704,893 and 6,074,341, both of which are entitled VESSEL OCCLUSIVE APPARATUS AND METHOD. The Timm-AUS is a one piece device not requiring saline filling or intra-operative assembly. Depression of a deactivation button through the scrotal skin causes a urethral occlusive sheath to expand and remove occlusive pressure from the urethra to allow normal urination. Depression of an activation button allows the occlusive sheath to contract and reapply urethral pressure to prevent urethral leakage. Human implantation experience with the Timm-AUS was hindered by formation of a tough, fibrous capsule surrounding the device which prevented expansion of the Occlusive Sheath.
Another mechanical method of occluding the urethra is demonstrated by U.S. Pat. No. 8,007,429 A1 entitled VESSEL OCCLUSIVE DEVICE AND METHOD FOR OCCLUDING A VESSEL. In this patent, depression of an activation button allows a constant force spring to apply tension to a compressible tape wrapped circumferentially about the urethra. In so doing, urinary leakage is prevented. Depressing a deactivation button removes spring tension and urethral compression to allow unobstructed urinary voiding.
A hybrid mechanical/hydraulic artificial urethral sphincter is described in US patent application publication 2010/0211175 A1 SURGICAL IMPLANT, IN PARTICULAR ARTIFICIAL SPHINCTER WITH ADJUSTED PRESSURE. This patent application publication describes a helical spring biased piston which maintains hydraulic pressure within an inflatable cuff circumferentially disposed about the urethral circumference. Depression of a secondary hydraulic bladder forces fluid from the piston into a third holding bladder to remove hydraulic pressure from the urethra. The pressurized fluid within this third bladder is then slowly discharged back into the piston through a fluid restrictor to re-establish hydraulic pressure about the urethra. Pressurized fluid may be locked out of the hydraulic cuff to remove pressure for a prolonged period as might be required immediately following implantation and during sleep when urinary leakage is not as problematic. Lockout is accomplished by depressing a lockout button. Returning the device to its normal function is accomplished by depressing the lockout button on its opposite side.
As evidenced by clinical experience with the above devices, it is difficult to teach the patient to identify and then operate the small lockout valve which is encased within and masked by scrotal tissues. Additionally, cuff refilling through the fluid restrictor takes 3 to 5 minutes. This allows ample time for the patient to believe that his bladder is empty and leave the commode. Residual urine within the bladder may then leak through the uncompressed urethra to wet the patient's clothing.